Micro- and nano-patterning of titanium surfaces for optimal osseointegration of orthopaedic implants

目前，由于需要支持身体的重量和功能，骨科医生仅限于他们可以用于承重关节置换(例如膝盖和髋关节)的材料类型。常用的是钛(钛)及其合金。然而，这种手术的寿命有限，因为缺乏与金属的直接骨接触，软组织形成加剧了这种接触；这使得微运动和最终失败。外科医生面临着越来越大的压力，原因首先是人口老龄化(1950年发达国家20岁以下人口与65岁以上人口之比为9.3，到2025年这一比例预计为0.59：65岁以上人口)以及与类风湿性关节炎相关的问题，其次是年轻人更加活跃的运动以及与骨关节炎相关的问题。由于这些手术目前的寿命(在挪威一项对4762例手术的研究中，髋关节翻修手术的10年失败率为26%)，患者将不得不带着疼痛等待更长时间，外科医生才会考虑手术。由于金属的材料特性，金属很难处理，因此迄今为止通过表面处理来鼓励直接骨生长从而开发出终身植入物的成功是有限的。我们最近证明，材料表面形貌中的特定纳米级线索可能意味着干细胞向骨的分化和干细胞向纤维组织的分化之间的差异。此外，我们认为，这仅仅是对通过纳米级设计可以获得的一系列效果的介绍。材料表面如此微小的变化可以对干细胞产生如此大的影响，这清楚地表明，纳米级设计可能对骨科生物材料的合理设计产生重大影响。开发诸如生物活性承重杆等“智能”骨科生物材料的关键问题是：(1)形成合适材料(例如钛)的能力，这是以前除了使用非特定和随机粗加工之外从未实现的，(2)实现机械交错(微特征)和直接骨结合(纳米线和微线)，以及(3)利用该技术生成原型设计，这将使行业能够扩大和开发，从而显著影响和造福患者的健康。

Currently, orthopaedic surgeons are limited to the type of materials they can use in load bearing joint replacements (e.g. knee and hip) due to the need to support the weight and function of the body. Commonly used are titanium (Ti) and its alloys. Such procedures, however, have a limited lifespan due to a combination of lack of direct bone contact with the metal exacerbated by soft tissue formation; this allows micromotion and ultimately failure. Surgeons face a mounting pressure due to firstly an aging population (in the developed world in 1950, there were 9.3 people under 20 for every person over 65, by 2025 this ratio is forecast to be 0.59 people under 20 for every person older than 65) and associated problems of rheumatoid arthritis and secondly a more sports active younger populations and problems associated with osteoarthritis. Due to the present lifespan of these procedures (The 10 year failure rate for revision hip surgery was 26% in a Norwegian study of 4762 operations) patients will have to wait longer with pain before surgeons will consider operations. The metals are hard to work with due their material properties and so success to date with surface treatments to encourage direct bone growth and hence develop implants for life have been limited.We have recently demonstrated that specific nanoscale cues in the topography of a material surface can mean the difference between stem cell differentiation to bone and stem cell differentiation to fibrous tissue. Furthermore, we believe that this is merely an introduction to the range of effects obtainable through nanoscale design. That such small alterations in the material surface can have such large effects on stem cells makes it clear that nanoscale design could have significant impact in the rational design of orthopaedic biomaterials. Crucial issues for the development of 'intelligent' orthopaedic biomaterials such as bioactive load-bearing stems are: (1) ability to pattern into suitable materials (e.g. Ti) this has not previously been achieved other than using non-specific and random roughening, (2) achieving both mechanical interdigitation (microfeatures) and direct bone bonding (nanocues and microcues) and (3) generating prototype designs using this technology, which will permit the scale-up and development by industry thereby significantly impacting and benefiting patient health.